This study aimed to compare epithelial cells derived from human embryonic stem cells （hESCs） to human ameloblast-lineage cells （ALCs）, as a way to determine their potential use as a cell source for ameloblast regeneration. Induced by various concentrations of bone morphogenetic protein 4 （BMP4）, retinoic acid （RA） and lithium chloride （LiCI） for 7 days, hESCs adopted cobble-stone epithelial phenotype （hESC-derived epithelial cells （ES-ECs）） and expressed cytokeratin 14. Compared with ALCs and oral epithelial cells （OE）, ES-ECs expressed amelogenesis-associated genes similar to ALCs. ES-ECs were compared with human fetal skin epithelium, human fetal oral buccal mucosal epithelial cells and human ALCs for their expression pattern of cytokeratins as well. ALCs had relatively high expression levels of cytokeratin 76, which ,vas also found to be upregulated in ES-ECs. Based on the present study, with the similarity of gene expression with ALCs, ES-ECs are a promising potential cell source for regeneration, which are not available in erupted human teeth for regeneration of enamel.

The periodontal ligament-derived mesenchymal stem cell is regarded as a source of adult stem cells due to its multipotency. However, the proof of chondrogenic potential of the cells is scarce. Therefore, we investigated the chondrogenic differentiation capacity of periodontal ligament derived mesenchymal stem cells induced by transforming growth factor （TGF）-β3 and bone morphogenetic protein （BMP）-6. After isolation of periodontal ligament stem cells （PDLSCs） from human periodontal ligament, the cells were cultured in Dulbecco＇s modified Eagle＇s medium （DMEM） with 20% fetal bovine serum （FBS）. A mechanical force initiated chondrogenic differentiation of the cells. For chondrogenic differentiation, 10 μg ·L-1 TGF-β3 or 100 μg ·L-1 BMP-6 and the combination treating group for synergistic effect of the growth factors. We analyzed the PDLSCs by fluorescence-activated cell sorting and chondrogenesis were evaluated by glycosaminoglycans assay, histology, immunohistochemistry and genetic analysis. PDLSCs showed mesenchymal stem cell properties proved by FACS analysis. Glycosaminoglycans contents were increased 217% by TGF-β3 and 220% by BMP-6. The synergetic effect of TGF-β3 and BMP-6 were shown up to 281% compared to control. The combination treatment increased Sox9, aggrecan and collagen II expression compared with not only controls, but also TGF-β3 or BMP-6 single treatment dramatically. The histological analysis also indicated the chondrogenic differentiation of PDLSCs in our conditions. The results of the present study demonstrate the potential of the dental stem cell as a valuable cell source for chondrogenesis, which may be applicable for regeneration of cartilage and bone fracture in the field of cell therapy.

In the present study, we investigate the expression profile of the epidermal growth factor receptor family, which comprises EGFR/ ErbB 1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4 in oral leukoplakia （LP）, The expression of four epidermal growth factor receptor （EGFR） family genes and their ligands were measured in LP tissues from 14 patients and compared with levels in 10 patients with oral lichen planus （OLP） and normal oral mucosa （NOM） from 14 healthy donors by real-time polymerase chain reaction （PCR） and immunohistochemistry. Synchronous mRNA coexpression of ErbB1, ErbB2, ErbB3 and ErbB4 was detected in LP lesions. Out of the receptors, only ErbB4 mRNA and protein was more highly expressed in LP compared with NOM tissues. These were strongly expressed by epithelial keratinocytes in LP lesions, as shown by immunohistochemistry. Regarding the ligands, the mRNA of Neuregulin2 and 4 were more highly expressed in OLP compared with NOM tissues. Therefore, enhanced ErbB4 on the keratinocytes and synchronous modulation of EGFR family genes may contribute to the pathogenesis and carcinogenesis of LP.

The objective of this study was to investigate the compositional profiles and microbial shifts of oral microbiota during head-and-neck radiotherapy. Bioinformatic analysis based on 16S rRNA gene pyrosequencing was performed to assess the diversity and variation of oral microbiota of irradiated patients. Eight patients with head and neck cancers were involved in this study. For each patient, supragingival plaque samples were collected at seven time points before and during radiotherapy. A total of 147232 qualified sequences were obtained through pyrosequencing and bioinformatic analysis, representing 3460 species level operational taxonomic units （OTUs） and 140 genus level taxa. Temporal variations were observed across different time points and supported by cluster analysis based on weighted UniFrac metrics, Moreover, the low evenness of oral microbial communities in relative abundance was revealed by Lorenz curves. This study contributed to a better understanding of the detailed characterization of oral bacterial diversity of irradiated patients.

A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than chlorhexidine. The aim of this study was to compare the antimicrobial activity of 1% alexidine with that of 2% chlorhexidine using Enterococcus faecalis.infected dentin blocks. Sixty bovine dentin blocks were prepared and randomly divided into six groups of 10 each. E. faecalis was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2% chlorhexidine or 1% alexidine solutions for 5 and 10 min, respectively. Sterile saline was used as a control. The antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron microscope. Significantly fewer bacteria were observed in the 2% chlorhexidine- or 1% alexidine-soaked groups than in the control group （P~O.05）. However, there was no significant difference in the number of bacteria adhering to the dentinal surface between the two experimental groups or between the two soaking time groups （P＞0.05）. Ruptured or antiseptic-attached bacteria were more frequently observed in the lO-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine groups. In conclusion, lO-min soaking with 1% alexidine or 2% chlorhexidine can be effective against E. faecalis infection.

This study investigated the efficacy of calcium hydroxide and chlorhexidine gel for the elimination of intratubular Candida albicans （C. albicans）. Human single-rooted teeth contaminated with C. albicans were treated with calcium hydroxide, 2% chlorhexidine gel, calcium hydroxide plus 2% chlorhexidine gel, or saline （0.9% sodium chloride） as a positive control. The samples obtained at depths of 0-100 and 100-200 μm from the root canal system were analyzed for C. albicans load by counting the number of colony forming units and for the percentage of viable C. albicans using fluorescence microscopy. First, the antimicrobial activity of calcium hydroxide and the 2% chlorhexidine gel was evaluated by counting the number of colony forming units. After 14 days of intracanal medication, there was a significant decrease in the number of C. albicanscolony forming units at a depth of 0-100 lzm with chlorhexidine treatment either with or without calcium hydroxide compared with the calcium hydroxide only treatment. However, there were no differences in the number of colony forming units at the 100-200 μm depth for any of the medications investigated. C. albicans viability was also evaluated by vital staining techniques and fluorescence microscopy analysis. Antifungal activity against C. albicans significantly increased at both depths in the chlorhexidine groups with and without calcium hydroxide compared with the groups treated with calcium hydroxide only. Treatments with only chlorhexidine or chlorhexidine in combination with calcium hydroxide were effective for elimination of C. albicans.

Regeneration of periodontal tissue is the most promising method for restoring periodontal structures. To find a suitable bioactive three- dimensional scaffold promoting cell proliferation and differentiation is critical in periodontal tissue engineering. The objective of this study was to evaluate the biocompatibility of a novel porcine acellular dermal matrix as periodontal tissue scaffolds both in vitroand in vivo. The scaffolds in this study were purified porcine acellular dermal matrix （PADM） and hydroxyapatite-treated PADM （HA-PADM）. The biodegradation patterns of the scaffolds were evaluated in vitro. The biocompatibility of the scaffolds in vivo was assessed by implanting them into the sacrospinal muscle of 20 New Zealand white rabbits. The hPDL cells were cultured with PADM or HA-PADM scaffolds for 3, 7, 14, 21 and 28 days. Cell viability assay, scanning electron microscopy （SEM）, hematoxylin and eosin （H＆E） staining, immunohistochemistry and confocal microscopy were used to evaluate the biocompatibility of the scaffolds. In vitro, both PADM and HA-PADM scaffolds displayed appropriate biodegradation pattern, and also, demonstrated favorable tissue compatibility without tissue necrosis, fibrosis and other abnormal response. The absorbance readings of the WST-1 assay were increased with the time course, suggesting the cell proliferation in the scaffolds. The hPDL cells attaching, spreading and morphology on the surface of the scaffold were visualized by SEM, H＆E staining, immnuohistochemistry and confocal microscopy, demonstrated that hPDL cells were able to grow into the HA-PADM scaffolds and the amount of cells were growing up in the course of time. This study proved that HA-PADM scaffold had good biocompatibility in animals in vivoand appropriate biodegrading characteristics in vitro. The hPDL cells were able to proliferate and migrate into the scaffold. These observations may suggest that HA-PADM scaffold is a potential cell carrier for periodontal tiss...

This paper aims to investigate if the dental restoration of nickel-chromium based alloy （Ni-Cr） leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of 〈 1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of 〈1, 1 to 〈3 and 3 to 〈6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

During smile evaluation and anterior esthetic construction, the anatomic and racial variations should be considered in order to achieve better matching results. The aims of this study were to validate an objective method for recording spontaneous smile process and to categorize the smile and upper lip curvature of Chinese Han-nationality youth. One hundred and eighty-eight Chinese Han-nationality youths （88 males and 100 females） ranged from 20 to 35 years of age were selected. Spontaneous smiles were elicited by watching comical movies and the dynamics of the spontaneous smile were captured continuously with a digital video camera. All subjects＇ smiles were categorized into three types： commissure, cuspid and gummy smile based on video editing software and final images. Subjects＇ upper lip curvatures were also measured and divided into three groups： upward, straight and downward. Reliability analysis was conducted to obtain intra-rater reliabilities on twice measurements. The Pearson Chi-square test was used to compare differences for each parameters （α=0.05）. In smile classification, 60.6% commissure smile, 33.5% cuspid smile and 5.9% gummy smile were obtained. In upper lip measurement, 26.1% upward, 39.9% straight and 34.0% downward upper lip curvature were determined. The commissure smile group showed statistically significant higher percentage of straight （46.5%） and upward （40.4%） in upper lip curvatures （P〈0.05）, while cuspid smile group （65.1%） and gummy smile group （72.7%） showed statistically significant higher frequency in downward upper lip curvature （P〈0.05）. It is evident that differences in upper lip curvature and smile classification exist based on race, when comparing Chinese subjects with those of Caucasian descent, and gender.

One-step apexification using mineral trioxide aggregate （MTA） has been reported as an alternative treatment modality with more benefits than the use of long-term calcium hydroxide for teeth with open apex. However, orthograde placement of MTA is a challenging procedure in terms of length control. This case series describes the sequence of events following apical extrusion of MTA into the periapical area during a one-step apexification procedure for maxillary central incisor with an infected immature apex. Detailed long-term observation revealed complete resolution of the periapical radiolucent lesion around the extruded MTA. These cases revealed that direct contact with MTA had no negative effects on healing of the periapical tissues. However, intentional MTA overfilling into the periapical lesion is not to be recommended.